Asphalt roofing



United States Patent ASPHALT ROGFIWG G. William Berry, Morris Plains,John C. Schmitt, Fair Lawn, and Joseph F. Schulz, Aliendale, N. J.,assignors to The Patent and Licensing Corporation, New York, N. Y., acorporation of Massachusetts No Drawing. Application July 2, 1056,Serial No. 595,130

3 Claims. (Cl. 108-7) This invention relates to improved asphalt roofingand more particularly to mineral surfaced asphalt roofing withoutsubstantial blistering.

For many years mineral surfaced asphalt roofing has been widely used asa roof covering material usually in the form of shingles. These shinglescomprise a rag or wood fiber felt saturated with asphalt and coated witha plastic asphalt in which are embedded roofing granules. The materialis then cut into any of a number of shapes and laid on roofs in avariety of well known patterns.

One of the difiiculties with these shingles is that they sometimesblister. If the blistering is pronounced, i. e., where the blisters arelarge and burst open or crater, the roof may eventually leak and have tobe replaced. The problem of blistering has been very widely investigatedfor a great number of years but its cure had not previously beenestablished.

It is therefore an object of the present invention to provide improvedasphalt mineral surfaced roofing without substantial blistering.

It is a further object of this invention to provide an improved asphaltshingle which can be consistently manufactured without substantialblistering.

These and other objects are attained by the present invention whichrelates to a roofing shingle wherein the felt base thereof is saturatedwith an asphalt to which oil has been added to bring the asphalt up to aspecified percentage of water white oil.

The analyses of asphalts to determine the content of water white oils isdescribed in The Journal of Research of the National Bureau ofStandards, at volume 54, No. 3 of March, 1955, by Lawrence R.Kleinschmidt. This procedure has been modified somewhat by theapplicants.

The procedure comprised first dissolving the asphalt in n-pentane. Thematerial insoluble in the n-pentane and separated by filtration is theasphaltene content. The npentane solution from a 5 gram sample ofasphalt after filtering out asphaltenes was concentrated from about 200cc. to 50 cc. by heating in a steam bath. An elongated tube was preparedcontaining a glass wool plug at the bottom thereof and a column offullers earth above in the weight ratio of 40:1 of fullers earth to theamount of the sample soluble in n-pentane (the Kleinschmidt method usesa ratio of 1). The fullers earth was first washed with n-pentane andthen the n-pentane containing the soluble portion of the asphalt waseluted through the fullers earth. The n-pentane solution passing throughthe fullers earth was evaporated by placing a beaker thereofapproximately 15 inches from a 250 watt infra-red lamp and the samplewas thus heated at 105 C. for about 15 minutes until the non-volatilefraction had reached a constant value. When all of the n-pentane hadbeen evaporated, the remaining fraction of the asphalt was a water whiteoil which has about the same viscosity as a heavy lubricating oil atroom temperature.

By the use of this modified Kleinschmidt method a sample of a Gulf Coastasphalt flux was found to have an 8% water white oil content. Gradualadditions of bright stock 2,804,833 Patented Sept. 3, 1957 lubricatingoil were mixed with the asphalt, testing after each addition, until atest indicated a water white oil content of 15%. The asphalt fluxmixture with oil was then airblown to form a saturating asphalt, i. e.,having a softening point of about 150 F. and a penetration of about 60at 77 F. Roofing felt was saturated in a molten bath of this asphalt andcoated with a coating asphalt by the usual method on a roofing machine.Roofing granules were then pressed into the plastic asphalt and thematerial cut into shingles.

Shingles made in accordance with the invention were tested in thefollowing manner. Cut pieces of shingle 6" x 6" were soaked in waterunder a vacuum of 27 inches of mercury for 5 minutes. They were thenallowed to stand 5 more minutes in the water bath at atmosphericpressure. The samples were then placed in an oven at 220 F. for twohours and examined for blisters. The following scale is used in theblister examination. Shingles giving a reading of 1 contain less than adozen small blisters, i. e., not over inch in diameter and raised notover inch above the shingle surface. Shingles rated 2 may contain manysmall blisters or a few large blisters or a few small open blisters(craters). Shingles rated 3 may contain a large number of largeblisters, a large number of small open blisters and may even containalso a few large open blisters. Shingles rated 4 contain a large numberof large open blisters.

In addition to this accelerated test shingles are also tested on anexposure rack subjected to atmospheric conditions. Experience indicatesthat at the end of two years of exposure the degree of blistering willusually have reached a maximum. Shingles which have not shown blisteringat the end of two years are not likely to blister on any furtherexposure. Shingles having a reading of 2 or less are not likely to causecomplaints, whereas shingles having a reading greater than 2 may beexpected to be the subject of complaints. By the term withoutsubstantial blistering as used herein is meant that an average readingfor a number of samples does not exceed 2 and that there are no largeopen blisters on any of the samples.

A number of samples of the shingles made in accordance with the exampleabove given accelerated tests averaging 1.3 as compared with shinglesmade with the same asphalt without the addition of oil which had anaverage of 2.8.

By saturating asphalt as used herein we mean the asphalt commonly usedin the roofing industry for saturating roofing felt. This asphalt has asoftening point in the range -160 F. and 40-80 penetration at 77 F. Itis airblown from asphalt flux which is a residue from petroleumdistillation having a softening point in the range 60-105 F.

In accordance with the invention the bright stock or crude lubricatingoil is added to the asphalt flux before air blowing.

Suflicient bright stock should be added to bring the water white oilcontent in the range 1520% by the modified Kleinschmidt method. Theamount of additional bright stock may be calculated roughly on the basisof the original modified Kleinschmidt test percentage as compared withthe desired water white oil percentage. However, subsequent modifiedKleinschmidt tests should be made to determine whether the proper amountof bright stock has been added to yield the water white oil content inaccordance with the test.

Exposure tests of about a year and a half confirm the accelerated teststhat the asphalt with a modified water white oil content substantiallyreduces blistering.

We claim:

1. An improved mineral surfaced asphalt roofing comprising roofing feltsaturated with saturating asphalt, a layer of coating asphalt on oneside thereof, and roofing A ima dm aaaal t ms ase as alt {Oofipg 9 prisi ng roofing felt saturated saturating asphalt, a laye coatingasphalt .on one side thereof arid roofing ran, t. mbi i q ii th 9 "2 a ah eam 1h? saturating asphalt the airb lol product of a Gulf Coast a hale i 'vi' mama K rii l vao t i 'a? t watfiti h tq Qi .qia a fi 11 flhi=hfia$b a a de before airblowing sufiicient Bright stock to obtain amodiai nm obfiaia-amq fi r hias Percentage of 4 fied Kleinschmidtpercentage of water white oil of about 15 W;

3. Mineral surfaced asphalt roofing shingles consistently showingfreedom from large open blisters comprising roofing felt saturated withsaturating asphalt, a layer of coating asphalt on one side thereof, androofing granules impressed in the coating asphalt wherein the saturatingasphalt is the airblown product of an asphalt flux to which mineral oilhas been added in an amount sufficient to obtain a modified Kleinschmidtpercentage of water white oil in the range 15-20%.

No references cited.

1. AN IMPROVED MINERAL SURFACED ASPHALT ROOFING COMPRISING ROOFING FELTSATURATED WITH SATURATING ASPHALT, A LAYER OF COATING ASPHALT ON ONESIDE THEREOF, AND ROOFING GRANULES IMPRESSED IN THE COATING ASPHALTWHEREIN THE SATURATING ASPHALT IS THE AIRBLOWN PRODUCT OF AN ASPHALTFLUX TO WHICH MINERAL OIL HAS BEEN ADDED IN AN AMOUNT SUFFICIENT TOOBTAIN A MODIFIED KLEINSCHIMIDT PERCENTAGE OF WATER WHITE OIL IN THERANGE 15-20%.